This invention relates to respirators in general and, in particular, to a new and useful respirator having an oxygen-delivering chemical cartridge and including means for determining whether the material of the chemical cartridge is still effective.
Respirators having an oxygen-delivering chemical cartridge are equipped with a gas-tight container. The container, which is usually in the form of a tank is necessary because the chemical cartridge, and particularly, the quick-starter contained therein, which ensures the production of oxygen in the first minutes of ventilation, are sensitive to moisture. The moisture would make the quick-starter and the oxygen-delivering cartridge unusable and, if provided, the CO.sub.2 -binding cartridge would also be unusable. Accordingly, it must be possible to determine the operable state at any given time.
Respirators are known which are equipped with filter materials which absorb water vapor from the surrounding air, and thus become unusable. Such filter materials, such as, Hopkalite, for example, are provided in filters which act against carbon dioxide. Other apparatus may contain carbon dioxide-binding cartridges, which, when filled with alkali hydroxide, also readily absorb water vapor. In order to prevent the change of the filter materials caused by water vapor, the respirators which are filled with these filter materials are arranged in special gas-tight containers. The tight seal of these respirators is determined by weight checks. Constancy of weight is an indication that the filter material is alright. In order to simplify the weight check, the apparatus can have a standard weight.
The operation of the respirators according to the invention cannot be determined by means of a weight check. Entering moisture leads to a chemical reaction, with the production of an equivalent amount of oxygen, which in turn, leads to constancy of weight (See German Pat. No. 1,022,095).
Another known respirator with water vapor-sensitive filling material has an inner container protecting at least the filling material, and an outer container surrounding the entire apparatus including the inner container. A drying agent is arranged in the space between the inner and outer container. This has the effect that no moisture, or hardly any moisture can accumulate in this space, so that hardly any moisture can diffuse into the inner container in the direction of the filling materials. The drying agent, e.g., blue gel, can show a complete or partial color change when a certain amount of moisture has been absorbed. This makes it possible to see, on the basis of the color of the drying agent, whether the respirator is still in good condition in respect to the penetration of moisture, or if it is already in danger.
The container of this respirator is a complicated double container. The drying agent which also acts as a moisture indicator keeps the space between the containers dry. It becomes moist after the outer container begins to leak. The moisture absorption of the filling material is determined by the tightness of the inner container. A simultaneous leakage of the outer container makes a dangerous moisture absorption of the filling material very likely. This amount of moisture missing in the moisture indicator then leads to a lower reading, which is then responsible for an incorrect evaluation of the operability of the device (See German Pat. No. 21 63 125).
A known device for indicating the tightness of a container for objects to be stored in a vacuum, e.g., respirator consists of a siphon connected with the interior of the container stored in a vacuum, which is arranged in a chamber sealed from the surrounding atmosphere. A ball is arranged in the space between the movable end wall of the siphon and the opposite chamber wall, which moves when the container is evacuated, that is, intact. When the container leaks and the vacuum is thus reduced, the siphon expands axially, thus reducing the interval. When the interval attains a clear height which corresponds to the diameter of the ball, the latter is immobilized. Its mobility is therefore an indication that the container is intact.
This known indicator can only be used in apparatus with a vacuum container. Beyond that, it requires a certain space for the movable siphon (German Patent Application No. P 28 24 175.0-27).